Related topics: solar wind · solar system

An artificial Proba-2 view of the solar north pole

We've sent numerous missions into space to study the Sun; past and present solar explorers include ESA's Proba-2 (PRoject for OnBoard Autonomy 2) and SOHO (SOlar Heliospheric Observatory) probes, NASA's SDO and STEREO missions ...

NASA Voyager 2 could be nearing interstellar space

NASA's Voyager 2 probe, currently on a journey toward interstellar space, has detected an increase in cosmic rays that originate outside our solar system. Launched in 1977, Voyager 2 is a little less than 11 billion miles ...

As solar wind blows, our heliosphere balloons

What happens when the solar wind suddenly starts to blow significantly harder? According to two recent studies, the boundaries of our entire solar system balloon outward—and an analysis of particles rebounding off of its ...

A day in the life of NASA's Voyagers

At more than 10 billion miles away from Earth, there is no day and night. Time and space are fathomless and our Sun is a distant point of starlight—a faint reminder of the home NASA's twin Voyagers, humanity's farthest ...

NASA's IBEX observations pin down interstellar magnetic field

Immediately after its 2008 launch, NASA's Interstellar Boundary Explorer, or IBEX, spotted a curiosity in a thin slice of space: More particles streamed in through a long, skinny swath in the sky than anywhere else. The origin ...

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The heliosphere is a bubble in space "blown" into the interstellar medium (the hydrogen and helium gas that permeates the galaxy) by the solar wind. Although electrically neutral atoms from interstellar volume can penetrate this bubble, virtually all of the material in the heliosphere emanates from the Sun itself. It was thought for decades that it extends in a long comet-like heliotail, but in 2009 data from the Cassini and IBEX show a different shape. However, depiction of the heliotail is still common. Another change is that the heliosheath area is not smooth but filled with magnetic bubbles.NASA 2011

For the first ten billion kilometres of its radius, the solar wind travels at over a million km per hour. As it begins to drop out with the interstellar medium, it slows down before finally ceasing altogether. The point where the solar wind slows down is the termination shock; then there is the heliosheath area; then the point where the interstellar medium and solar wind pressures balance is called the heliopause; the point where the interstellar medium, traveling in the opposite direction, slows down as it collides with the heliosphere is the bow shock.

As of June 2011, the heliosheath area is thought to be filled with magnetic bubbles (each about 1 AU wide), creating a "foamy zone". The theory helps explain in situ heliosphere measurements by the two Voyager probes.

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